Switch mechanism for electric motors.



Patented Jan. l4, I902.

' No. 69l,l87.

A. W; SGHRAMM. SWITCH MECHANISM FOR ELECTRIC MOTORS.

(Application filed 0ct.-80, 1899.]

5 Shets-Sheet l.

(N9 Model.).,

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Patented'jan.*!4,-|902. A. w.. SCHBAMM. v SWITCH MECHANISM FORELECTRI C MOTORS i (No Model.)

(Applicajsion filed 89, 1899.;

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Patented Ian. I4, 1902;

A. w. scHnAm'm. swncu MECHANISM FOBELEGTRIC MOTORS.

(Application med we. so. 1899.; fl i'm, Feid Gen. Gen. 17 salt 51 5 Sheets-Sheet 3 0.. wAsumr-You n c No. 691,187. Patented Ian. l4, I902.

. A. W. SCHBAMM.

SWHTGH MECHANISM FORELEGTRIC MOTORS.

(Application filed Oct. 30, 1899.) (No Model.) 5 Sheets-Sheet 4.

A. w. SCH RAMM. SWITCH MECHANISM FOR ELECTRIC M'OTQRS;

7 (Application filed Oct. 30, 1899.;

(No Model.) 5 Sheets-Sheet 5.

, mrwonms PETERS Co. PHOTO-LITMO WASNINGTON n. 0.,

UNITE STATES PATENT OFFICE.

,ADOLPI-I W. SCI-IRAMM, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO THE ELECTRO DENTAL MANUFACTURING COMPANY, OF CAMDEN, NEW JERSEY, A CORPORATION OF NEV JERSEY.

SWITCH MECHANISM FOR ELECTRIC Morons.

SPECIFICATION forming part of Letters Patent NO. 691,187, dated January 14, 1902. Application filed October 30. 1899. Serial No. 735,229- (No model.)

To all whom, it may concern.-

Be it known that I, ADOLPH W. SCHRAMM, a citizen of the United States, residing in Philadelphia, Pennsylvania, have invented cerrain Improvements in Switch Mechanism for Electric Motors, of which the following is a specification.

One object of myinvention is to so construct a switch for a shunt-wound electric to motor as to control the speed and direction of rotation of thearmature by change of potential and polarity at the armature brushes or coils while the current through the field is constant in direction and magnitude, a fur- :5 ther object being to close the circuit through both armature and field coils without-possibility of closing the armature-circuit unless the field-circuit is also closed.

A further object of the invention is to insure the quick stoppage of rotation of the armature when the current is cut off from the same.

The change in potential at the armature brushes or coils of the motor is effected by connecting said armature brushes or coils to various points of a subdivided resistance connected to the supply-wires from the generator or to various terminals of a subdivided battery when the latter is the source of our- 0 rent. Change of polarity of the armature brushes or coils and varying of potential are efiected by the employment oftwo movable contacting devices, which for convenience may be termed brushes, one acting to se- 5 'lect the potential when the current is flowing in onedirection and the other acting to select thepotential when the current is flowing in the opposite direction. Quick stoppage of the armature is effected by the employment 40 of a relay-magnet and switch, whereby the field-circuit is always kept closed when there is anycurrent in the armature-circuit,whether said current is derived from the generator or I is due to the rotation of the armature'acting 5 as a dynamo after the generator-current has been cut off from the same.

The mechanism of my improved switch comprises, essentially, the two potential-selecting brush-levers, each having an armature connection and each acted upon by a spring tending to move it to a neutral point, each of these levers being independently moved by means of a third lever, which is preferably made in two parts and which serves to move one of the potential-selecting brushlevers through a certain path on one side of the neutral point and the other lever through a certain path on the opposite side of said neutral point, said third lever also operating the circuit making and breaking switch and having arms or projections which engage with the fixed frame so as to retain the lever in "different positions of adjustment. These parts, as well as the necessary electrical contact-pieces and binding-posts, are carried by a suitable frame,which is preferably so mounted in an inclosing casing or box that it can be readily removed therefrom for inspection or repairs without disturbing the relative positions of the parts.

In the accompanying drawings, Figure 1 is a longitudinal section, partly in elevation, of part of an electrical switch constructed in ac cordance with my invention. Fig. 2 is a vertical section of part of the same, showing the method of mounting the various levers of the device. Figs. 3 and 4 are sectional plan views showingdifferent positions of the main operating-lever. Fig. 5 is a view showing the various' superposed parts of the switch separated from each other, so as to illustrate more clearly their construction and the electrical connections between them, the switch shown in this view being intended for use when the. generator of electricity employed is a battery. Fig. 6 is a view likewise showing separated from each other the superposed parts of a switch intended for use when the current employed is an electric-lighting current or other current of high voltage. Fig. 7 is a diagram illustrating the electrical connections of the battery-switch. Fig. 8 is a diagram representing the electrical connections of the highvoltage switch. Fig. 9 is a diagram similar to Fig. 8, but showing the application of the 5, relay magnet and switch; and Fig. 10 is a sectional view illustrating a modification of my invention.

Referring first to Figs. 1 to 6, it will be observed that a rectangular vertical frame 1 carries a vertical spindle or pin 2, around which the various levers of the switch are caused to swing, said frame 1 having at one side a supplementary segmental frame 3, which carries a series of electrical contactpieces,referred to hereinafter. The lower portion of the frame 1 also has a segmental bar 4, of insulating material, upon which are mounted the binding-posts, screws, or other connections for the various wires leading to the switch. The axial 'pin 2 of the switch is surrounded by a sleeve 5, to which is secured a lever 6 and a block '7, a pin 8 on this block being acted upon by the lower end of a coiled spring 9, so that one arm of the lever 6 is normally held in contact with a stop-lug 10, projecting downward from a segmental bar 11, mounted on the frame 1, the other arm of said lever 6 carrying a pair of spring-fingers 12, which are suitably insulated from the lever and are adapted to operate in connection with certain of the electrical contactpieces carried by the frame 3, as described hereinafter, these spring-fingers thus constituting one of the contact-brushes before mentioned.

Mounted upon the sleeve 5 so as to turn freely thereon is another sleeve 13, secured to or forming part of a lever 13, which has a pin 14, acted upon by the upper end of the coiled spring 9, the effect of which is to maintain one arm of said lever 13 in contact with the opposite side of the stop-lug 10 from that against which the lever 6 bears, the other arm of said lever 13 likewise carrying a pair of spring contact-plates 15, which are suitably insulated from the lever, are adapted to act in connection with certain of the electrical contact-pieces mounted upon the frame 3, and constitute the other of the brushes before mentioned.

Mounted upon the pin 2, above the sleeve 5, is another sleeve 16, to which is secured one element 17 of a compound or duplex lever, the other element 18 of said lever projecting beyond the casing 19 of the switch and having adownwardly bent or depending and widened outer end, so that it can be readily operated by a sidewise pressure of the foot, said element 18 being fulcru med upon the element 17 by means of a screw-pin 20, carried by the element 18 and adapted to an opening in the element 17, and said element 18 of the lever also having laterally-projecting arms 21 and 22, which coact with certain teeth 28 in the v notched segmental bar 11 to hold the element 18indifferentpositionsofadjustment,ashereinafter described. Projecting downwardly from the element 18 of the lever is a'lug 23, which fits snugly between the levers 6 and 13 when said levers are in contact with the stoplug 10, as shown in Fig. 5. Secured to the sleeve 16 is an arm 24, which carries suitablyinsulated spring contact-arms 25, the latter operating in conjunction with a segmental switch-plate 26, mounted on the frame 1, but properly insulated therefrom, so as to constitute a'making and breaking switch for the current which supplies the motor. When the element 18 of the duplex operating-lever is in neutral position, as shown in Fig. 3, neither of its arms 21 nor 22 is in contact with the segmental bar, and the first effect of movement of the element 18 in either direction is to cause it to swing upon its fulcrum 20, because such movement is more readily efiected than a movement of the element 17 around the axial pin 2, owing to the retarding influence of the switch-arms 25, which are in frictional contact with the switch-plate 26. One or other of the arms 21 22 is thus brought into contact with its coacting portion of the segmental bar 11, further swinging movement of the lever being now around the axis of the pin 2, so as to carry said arm 21 or 22 along the toothed portion of the bar 11, the element 18 of the lever, however, being still free to turn upon its fulcrum 20 to the extent necessary to permit its arm 21 or 22 to pass over the teeth 28,

of the bar and said arm 21 or 22 being pressed forwardly against each tooth as it passes the same by the action of the spring 9 acting through the medium of the lever 6 or 13 until the lever finally reaches an extreme positionsuch, for instance, as that represented in Fig. 4, where the arm 21 is in engagement with the last tooth of the series, and further movement of the lever 13 is arrested by one of a pair of lugs 27 on the under side of the segmental bar 11, which lugs determine the extreme positions of the levers 6 and 13. In restoring the composite lever from an extreme positionsuch, for instance, as that represented in Fig. 4:--to the mid or neutral position pressure upon the projecting end of the element 18 of the lever effects in the first instance a rocking of said element 18 upon the pin 20 as a fulcrum until the engaging arm 21 or 22 is withdrawn from the tooth of the segmental bar with which it was in contact,swinging of the lever around the axial pin 2 being prevented because such movement is resisted by the bearing of the arm 21 or 22 upon the tooth 28. When the arm has been released from the control of the tooth, the leverswings backward upon the pin 2 as its axis, while the arm 21 or 22 is held free from the toothed portion of the bar 11 owing to the retarding action of-the friction-brake 25 26 upon the movement of the element 17 and the forward pressure of the spring 9 upon the element 18 through the medium of one of the levers 6 and 13. Hence the spring will restore the duplex lever to mid-position without any engagement of its arm 21 or 22 with the toothed portion of the bar 11, the pressure of the hand or foot freeing the arm 21 or 22 from the tooth with which it was in engagement and permitting the spring 9 to effect the return movement of the lever. The pin 2 constitutes, in efiect, a

primary fulcrum upon which both elements 17 and 18 can swing as a unit, and the pin 20 ICC -wire 0 constitutes a secondary fulcrum upon which the element 18 can swing independently of 22 strikes the outer faceof one of these stopteeth and forces the other arm into engagement with the inner face'of the opposite tooth, thus preventing the lever from passing beyond the mid-position by reason of momentum.

Instead of employing a frictional retarder for the element 17 of the duplex lever the element 18 may be so weighted that momentum exerted at a point on the opposite side of the pin 20 from that on whichv the manipulated portion of the arm projects will prevent either of the arms 21 or 22 of the lever from moving back into engagement with the teeth 28 after it has .been released therefrom in starting the return of the lever to the mid or neutral position. Such amomentum weight is shown at 18 in Fig. 10. The arm 18 might also be mounted upon the arm 17 by means of a horizontal pivot instead of by the vertical pivot 20, in which case the teeth 28 and 28 would be on the upper sidev of the segmental bar 11 instead of upon the inner side of the same.

The switch may be used in connection with a battery or a high-voltage current, the elec-' trical connections, when a battery is used, being understood on reference to Figs. 5 and 7. There are in this case binding-posts a, b, c, d, e, and f, the post a being connected by a wire a to one of the armature-brushes of the motor and also by a Wire a to the brush 12.

The post I) is connected by a wire I) to one terminal of the battery-say, for instance, the positive terminal-and is also connected by "a wire 19 tothe segmental switch-plate 26.

The post 0 is connected by a wire 0 to the negative terminal of the battery and also by a wire a to one of, the end contacts 0 of the segmental series of contacts carried by the bar 3, said contact 0 being connected to the opposite end contact 0 by a wire 0 The post 0 is also connected to the post d by a The post 6? is connected by a wire (1 to the negative terminal of the field. 'The post e is connected by a wire e to the positive terminal of the field and also by a wire e to an intermediate plate e of the series of,

The postfis connected by connected to the contact 71 by means of a wire h The contacts 9 h and i are connected by wires 9 b and 11 respectively, to negative terminals of different cells or groups of cells of the battery, as shown in Fig. '7. Thus the contact 2' may be connected to the negative terminal of-the first cell or group of cells, the contact 71, to the negative terminal of .the second cellor group of cells, the contact g to the negative terminal of the third cell or group of cells, and the contact 0 to the negative terminal of the fourth cell or group of cells, it

. being understood that all of the cells or groups of cells of the battery are connected in series. Supposing that the parts are adjusted to the position shown in Fig. 7-that is to say, the

current-controlling switch 25 is moved into contact with the switch-plate 26, so as to close the supply-circuit, and the brush 15 is moved ontothe contact t -the battery-current willbe passed through the field-coils, the flow of current being'from the positive pole of the battery through 17, I), h 26, 25, e e c and c to the positive terminal of the field-coil and from the negative terminal of the latter back through d, d, 0 c, and c to the negative terminal of the battery. The armature-coils receive current from one of the cells or groups of cells of the battery, the flow of current being from the positive terminal of the battery through I), b, 19 26, 25, e e 12, a a, and a to the positive brush of the armature and from the negative brush back through f, f, f 15, t and t to the negative terminal of the first cell or group of cells. When the brush 15 is moved onto the contact h the potential of the second cell or group of cells will be impressed upon the armature-terminals, and when said brush is moved onto the contact g the potential of the third cell or group of cells will be impressed upon said terminals, while when the brush 15 is moved onto the contact 0 the armature-terminals will have the entire battery -.potential. When the operating-lever is moved in the opposite direction, a change of polarity in the current supplied to the armature results, the positive brush of the armature being new that communicating with the post f and the negative brush that communicating with the post CL, and consequently the direction of rotation of the armature will be reversed. But two degrees of potential are provided for when the armature is reversed, as will be readily understood from the connection shown in Fig. 7. In adapting the switch to high-tension currents substantially the same connections are used; but the contacts c 9 71 and t are connected to various points of a subdivided resistance. Thus, as shown inFigs. 6 and 8, said resistance comprises four groups of coils O, G, H,

and I, connected in series, but each having b leading from c to the post 1). Between the coils O and G a wire g leads to the contact 9 Between the coils G and H a wire 71 leads to the contact 7L3, and between the coils H and I a wire 1' leads to the contact 2' The other terminal of the coil I is connected to the post a by means of a wire As shown in Figs. 6 and 8, the binding-post connections are somewhat different from those in Figs. 5 and '7, the posts I) and c communicating with the field-terminals and the posts (1 and c with the wires leading to the generator, the post I) being connected to the switch 25, the post 6 to the switch-plate 26, and the post cl to the plate 6 the posts I) and 0 being connected to the opposite terminals of the series of resistance-coils. When the parts are in the position shown in Fig. 8, the current flows from the positive pole of the generator through c, e, 6 26, 25, 11 Z), and Z) to the positive terminal of the field-coils and back from the field through c, 0, c cl, and d to the negative pole of the generator. The current flows to the positive brush of the armature from the positive pole of the generator through c, e, 2 26, 25, 12 19, b 0 c, c, 0 C, G, H, F, i 15, f f, andf to the positive brush of the armature and back from the negative brush of the armature through a, Ct, a 12, 6 (1 d, and d to the negative pole of the generator. After passing through the coil H the current divides, part returning to the generator through the coil I and o c d (1'. Hence the potential at the armature is that represented by the potential difference at the ends of the coil I. WVhen the brush is on the contact 7L3, the potential at the armature is that represented by the potential difference at the ends of the coils I H, and in like manner contact of 15 and g gives the armature the potential difference between the ends of the coils I, H, and G, and contact 15 and 0 gives the armature the potential difference between the ends of the whole series of coils. Reversal of the potential and the variation of the reverse potential are efiected in the same manner as when the battery is employed.

It will be observed that the'full strength of the current is always maintained in the fieldcoils whether the armature is rotated in one direction or the other, change in speed being effected by varying the potential of the armature-coils and change in direction of rotation bychanging their polarity. The circuit-closing switch is so arranged that the potential of the generator or battery is simultaneously impressed on the field-coils and segmental series of contact-pieces,making it impossible for the armature to take current before current passes through the field. In fact, the field receives the current in advance of the armature, since the brush 12 or 15 does not make contact with 11 or it until after the switch has made contact with the switch-plate 26. When both of the brushes 12 and 15 bear upon the contact 6 the potential difference of the armature-brushes is zero; but the first movement of the switch after closing the circuit supplies to the armature-coils current due to a potential represented by the first section of the subdivided resistance or battery, further movement of the switch gradually increasing the potential from the resistance or battery, as will be readily understood.

It will be noted that the frame 1 carries all of the operative mechanism and internal connections of the switch, so that it can be readily removed from the casing 19 for inspection, cleansing, repair, or other purposes without disturbing any of said operating parts or internal connections.

In order to effect. quick stoppage of rotation of the armature, I use a switch controlled by a relay-magnet, whereby the fieldcircuit is maintained after the potential of the armature is brought to zero, so that the latter rotates in a magnetic field which acts as a magnetic brake on the armature. This arrangement is illustrated in Fig. 9, on reference to which it will be observed thatI have added to the connections shown in Fig. 8 a

magnet 30, which is always maintained in the armature-circuit by coiling the wiref around it in its course from f to 15. The armature 31 of the magnet constitutes one terminal of a relay-switch and is connected by a wire I) to the field-wire 11 The other terminal 32 of the relay-switch is connected by a wire 6 to the switch-plate 26. The switch 31 32 is of course kept closed when current is being supplied to the motor, as the magnet is in the armature-circuit, and said switch 31 32 is then a shunt to the circuit-switch 25 26. WVhen the battery or generator current is cut off from the armature, there will still be current in the armature-circuit so long as the armature is rotating in a magnetic field, and this magnetic field will be maintained by the switch 31 32, which now serves to direct the supply-current to the field-coils and is kept closed so long as there is rotation of the armature. This constitutes a magnetic brake on the armature and serves to bring the same quickly to rest, the switch 31 32 then opening and cutting out the field-coils of the motor.

It will be noted that the resistance-coils O, G, H, and I form a shunt to the field-circuit, and hence provide for the flow of current arising from self-induction in the field, thereby precluding the generation of a cur- .rent of high voltage in the field-coils from this cause.

Having thus described my invention, I claim and desire to secure by Letters Patent- 1. The combination in an electric switch, of generato nterminals, motor-field terminals, and armature-terminals,a circuit making and breaking switch, connections whereby the current is directed to the field-coils when the switch is closed, contacts connected to various subdivisions of a resistance permanently connected between the field terminals, and a potential-selecting brush and connections whereby the potential at the armature is represented by the potential difference between the ends of one or more of the subdivisions of the resistance, substantially as specified.

2. The combination in an electric switch, of a pair of 1 otential-selecting levers, means for maintaining them normally in neutral position and an operating-lever moving in a plane parallel with that of the potential-selecting levers and having a portion interposed between said pot'ential-s'electin g levers, wh ere by when" moved in one direction, it will operate one lever and when moved in the other direction will operate the other lever, substantially as specified. r

3. The combination in an electric switch, of a pair of potential'selecting levers, means for maintaining them normally in neutral position, an operating-lever having a portion interposed between said potential-selecting levers, whereby when moved in one direction it will operate one lever, and when moved in the other direction will operate the other lever, and a circuit making and breaking switch also controlled by said operating-lever, substantially as specified.

at. The combination in an electric switch, of a pair of potential-selecting levers, means for maintaining them normally in neutral position, an operating-lever, having a portion interposed between said potential-selecting levers, whereby when moved in one direction it will operate one lever, and when moved in the other direction will operate the other le- Ver, and means for maintaining said operating-lever in its variouspositions of adjustment, substantially as specified.

5. An electric switch in which are combined a pair of potential-selecting levers mounted so as to swing on a common axis, a coiled spring acting in onedirection upon one of said levers and in the other direction on the other lever, a stop whereby said levers are maintained normally in neutral position, and an operating-lever having a portion for acting upon one of said potential-selecting levers to move it in one direction, and upon the other of said levers to move it in the opposite direction, substantially as specified.

6. An electric switch in which are combined a toothed bar, and a switch-lever having a pivotal mounting whereby an arm of said lever is caused to engage with the teeth of the bar when the lever is moved in one direction in respect to said teeth but swings clear of the teeth of the bar when the lever is moving in the opposite direction in respect thereto,

substantially as specified.

7. In an electric switch, the combination of a duplex lever composed of two elements, the

different positions of adjustment, substantially as specified.

8. In an electric switch, the combination of a duplex lever composed of two elements, the first having a primary fulcrum upon which both elements can swing as a unit, and the second element having a fulcrum upon the first, on which it can swing independently, a toothed segment engaging with an arm of said second element to maintain it in its different positions of adjustment, and a spring acting on said second element to restore it to its primary position when its arm is freed from engagement with said teeth, substantially as specified.

9. In an electric switch, the combination of a duplex operating-lever composed of two elements, the first having a primary fulcrum upon which both can swing as a unit, and the second element having a fulcrum upon the first on which it can swing independently, a toothed retainer for an arm on said second element, and means for preventing back movement of the second element after it has been swung on its fulcrum independently of the first to free'its arm from the control of said toothed retainer, substantially as specified.

10. In an electrieswitch,the combination of a duplex operating-lever composed of two elements, the first having a primary fulcrum upon which both can'swing as a unit, and

the second element having a fulcrum upon the first on which it can swingindependently, a toothed retainer for said second element, and a frictional retarding device for the first element, substantially as specified.

11. An electric switch in which are combined a lever and a segment having teeth, said lever being provided with an arm constructed to be moved into engagement with the toothed segment for maintaining the lever in any desired position, mechanical means for returning the lever to an off position, and a stop-tooth placed to come in contact with said arm for arresting the motion thereof when the lever returns to its off position under the influence of said mechanical means, substantially as described.

12. An electric switch in which are combined a lever having oppositely-extending arms, and a segment having teeth for engaging with each of said arms to retain the lever in its different positions of adjustment to right or left, and stop-teeth for arresting movement of either arm when the lever reaches a neutral position, substantially as specified.

13. An electric switch in which are combined motor-field terminals, connections for IIO and ai'matlire-terminals, a main circuit makname to this specification in the presence of ing and breaking switch controlling both field two subscribing witnesses. and armature, and a magnetic relay-switch 7 controlling the field-circuit independently of ADOLPH SCHRAMM' the main switch and having its magnet in the I \Vitnesses: armature-circuit, substantially as specified. JOS. H. KLEIN,

In testimony whereof I have signed my F. E. BEOHTOLD. 

